Manchin is more useful as a D. Better to reach across the aisle, and expect him to vote against R’s on issues important to WV that are more liberal (union issues, etc)
If Manchin had decided to switch a few months ago, he could have written his own ticket...as far as committee assignments, and getting credit for his seniority. However, the GOP faces a tougher Senate cycle in 2016, so adding another seat to the caucus is a good thing..